Mutations in chikungunya virus nsP4 decrease viral fitness and sensitivity to the broad-spectrum antiviral 4′-Fluorouridine

• Published in: PLoS pathogens Vol. 21; no. 1; p. e1012859
• Main Authors: Yin, Peiqi, Sobolik, Elizabeth B., May, Nicholas A., Wang, Sainan, Fayed, Atef, Vyshenska, Dariia, Drobish, Adam M., Parks, M. Guston, Lello, Laura Sandra, Merits, Andres, Morrison, Thomas E., Greninger, Alexander L., Kielian, Margaret
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 13.01.2025; Public Library of Science (PLoS)
• Subjects: Animals; Antiviral agents; Antiviral Agents - pharmacology; Biology and life sciences; Chikungunya Fever - drug therapy; Chikungunya Fever - virology; Chikungunya virus; Chikungunya virus - drug effects; Chikungunya virus - genetics; Control; Dosage and administration; Drug Resistance, Viral - genetics; Genetic aspects; Humans; Medical research; Medicine and Health Sciences; Medicine, Experimental; Mice; Mutation; Physiological aspects; Viral genetics; Viral Nonstructural Proteins - genetics; Viral proteins; Virus Replication - drug effects; Virus Replication - genetics; United States
• ISSN: 1553-7374; 1553-7366; 1553-7374
• DOI: 10.1371/journal.ppat.1012859

Chikungunya virus (CHIKV) is an arthritogenic alphavirus that has re-emerged to cause large outbreaks of human infections worldwide. There are currently no approved antivirals for treatment of CHIKV infection. Recently, we reported that the ribonucleoside analog 4′-fluorouridine (4′-FlU) is a highly potent inhibitor of CHIKV replication, and targets the viral nsP4 RNA dependent RNA polymerase. In mouse models, oral therapy with 4′-FlU diminished viral tissue burdens and virus-induced disease signs. To provide critical evidence for the potential of 4′-FlU as a CHIKV antiviral, here we selected for CHIKV variants with decreased 4′-FlU sensitivity, identifying two pairs of mutations in nsP2 and nsP4. The nsP4 mutations Q192L and C483Y were predominantly responsible for reduced sensitivity. These variants were still inhibited by higher concentrations of 4′-FlU, and the mutations did not change nsP4 fidelity or provide a virus fitness advantage in vitro or in vivo. Pathogenesis studies in mice showed that the nsP4-C483Y variant caused similar disease and viral tissue burden as WT CHIKV, while the nsP4-Q192L variant was strongly attenuated. Together these results support the potential of 4′-FlU to be an important antiviral against CHIKV.